Patch 3.1 – we’ve been waiting for it.

Could you please tell me where to download patch 3.1 for version 1.50?

There is no such patch 3.1 for version 1.5. Patches starting from version 1.1 up to version 1.6 are intended only for the original version of Heroes 5. Moreover, patch 1.4 is cumulative, meaning it can be installed on any original game version from 1.0 to 1.3. The remaining patches are installed one after another (1.1, 1.2, 1.3, and so on). For version 1.5, there is patch version 1.6. By the way, version 1.6 makes the original game practically identical to Tribes of the East, with the exception of the Orc faction, alternative upgrades, and some minor differences...

3.1 is installed only on Tribes of the East version 3.0.